An O-ring, also known as a packing, or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.
O-rings are one of the most common seals used in machine design because they are inexpensive, easy to make, reliable and have simple mounting requirements. They can seal tens of megapascals (thousands of psi) of pressure. The O-ring may be used in static applications or in dynamic applications where there is relative motion between the parts and the O-ring. Dynamic examples include rotating pump shafts and hydraulic cylinder pistons.
O-ring materials may fail because of high or low temperatures, chemical attack, vibration, abrasion, and movement. Elastomers are selected according to the situation.
There are O-ring materials which can tolerate temperatures as low as 73K or as high as 523K. At the low end, nearly all engineering materials become rigid and fail to seal; at the high end, the materials often burn or decompose. Chemical attack can degrade the material, start brittle cracks or cause it to swell. For example, NBR seals can crack when exposed to ozone gas at very low concentrations, unless protected. Swelling by contact with a low viscosity fluid causes an increase in dimensions, and also lowers the tensile strength of the rubber. Other failures can be caused by using the wrong size of ring for a specific recess, which may cause extrusion of the rubber.
A traditional O-ring is typically the structure shown in FIG. 1. Please refer to FIG. 1, which illustrates the configurations and mounting setting of the traditional O-ring. Generally, the traditional O-ring 102 is disposed in a groove 104 of an electronic product 100 and must be pushed inwards and to the bottom of the groove 104, so as to achieve the waterproof function when being combined with a protruded edge of a housing. However, the traditional O-ring suffers from some problems. For example, if the O-ring is not completely pushed to the bottom of the groove 104 when being mounted and only part of the O-ring is pushed to the bottom, part of the O-ring fits the protruded edge of the housing and the other part of the O-ring is not attached to the protruded edge of the housing during assembly, which will cause water to penetrate into the electronic product. In other words, the waterproof function of the traditional O-ring can be reduced or fail easily because different persons or different machines assemble the electronic product in different ways.
Therefore, there is still a need for a solution which can solve the problem that the waterproof function of the traditional O-ring can be reduced or fail easily because of different assembling methods.